US3909890A

US3909890A - Method for heat-treating knitted fabric in tubular distended form

Info

Publication number: US3909890A
Application number: US358505A
Authority: US
Inventors: Robert Frezza
Original assignee: Samcoe Holding Corp
Current assignee: Samcoe Holding Corp
Priority date: 1972-01-24
Filing date: 1973-05-09
Publication date: 1975-10-07
Anticipated expiration: 1992-10-07

Abstract

Methods are provided for heat treating knitted fabric in tubular form, particularly synthetics in a manner whereby contact marks or lines on the internal surfaces of such fabric are substantially avoided by the utilization of a frame configuration for the spreader therefor which eliminates continuous horizontal contact with the internal surface of the fabric during treatment with a spreader comprised of a series of criss-cross connected frames which present only a series of sequential contact areas against the internal surface of the fabric. In addition, positive cooling is provided in combination with the heat treating methods for defining the end of the heat treating zone. Also included herewith is an arrangement for selectively delivering the heat treated fabric in a tubular form or an open width form, and for accommodating either a pre-dyeing step or a post-dyeing step in tubular form.

Description

Frezza Oct. 7, 1975 METHOD FOR HEAT-TREATING KNITTED FABRIC IN TUBULAR DISTENDED FORM [75] Inventor: Robert Frezza, Carle Place, N.Y.

[73] Assignee: Samcoe Holding Corporation,

Woodside, N.Y.

[22] Filed: May 9, 1973 [21] Appl. No.: 358,505

Related 1.1.8. Application Data [62] Division of Ser. No. 220,277, Jan. 24, 1972, Pat. No.

674,091 11/1963 Canada 26/55 C Primary ExaminerRobert R. Mackey Attorney, Agent, or Firm-Mandeville and Schweitzer 57 ABSTRACT Methods are provided for heat treating knitted fabric in tubular form, particularly synthetics in a manner whereby contact marks or lines on the internal surfaces of such fabric are substantially avoided by the utilization of a frame configuration for the spreader therefor which eliminates continuous horizontal contact with the internal surface of the fabric during treatment with a spreader comprised of a series of criss-cross connected frames which present only a series of sequential contact areas against the internal surface of the fabric. In addition, positive cooling is provided in combination with the heat treating methods for defining the end of the heat treating zone. Also included herewith is an arrangement for selectively delivering the heat treated fabric in a tubular form or an open width form, and for accommodating either a pre-dyeing step or a post-dyeing step in tubular form.

8 Claims, 4 Drawing Figures US. Patent 0%11975 Sheet 2 0m 399,9

US, Pamm 06:. 7,1975 Sheet 3 01 3 $99 Hum METHOD FOR HEAT-TREATING KNITTED FABRIC IN TUBULAR DISTENDED FORM This is a division of application Serial No. 220,227, filed Jan. 24, 1972 now US. Pat. No. 3,762,003 granted Oct. 2, 1973. 1

Generally speaking, this invention relates to methods for the heat treatment of fabrics. More particularly, this invention relates to methods for heat treating tubular knitted fabrics, including those comprised of synthetic fibers in which the tubular knitted fabric is heat treated in a form appropriate for subsequent use, and with the methods herein eliminating substantially the contact lines usually associated with the heat treatment of such fabrics by the utilization of an arrangement of spreader in the treating zone which presents only sequential intermittent contact against the internal surface of the tubular knitted fabric as it proceeds through the apparatus.

As will be understood, the utilization of heat treatment for tubular knitting fabrics has been carried out for some time, especially for providing drying of such fabrics subsequent to previous moisture impregnating steps such as the application of steam, dye or no press" resins with the heat treating usually being utilized for removing such moisture while the tubular knitted fabric is held in its tubular distended form as desired so as to provide a final product either in tubular form or open width form which retains its desired distended characteristics. As will be understood, further, in commercial operations, many yards of such tubular fabric may be processed in a single production run, and, as is obvious, if contact marks have been imparted to the fabric edges, then the commercial value of the fabric is reduced because that portion of the fabric with marks must be either cut off or not usedin garment manufacture.

Further, with the advent of synthetic fibers, such problems as the avoidance of marks during processing of tubular knitted fabric comprised of such synthetic fibers became even more difficult because the heat treating operations serve to actually set permanently the marks into the synthetic tubular knitted fabric. Because of the nature of synthetics, such as polyesters or nylon, for example, the application of heat in many instances affects to differing degrees the molecular structure of the fibers of such fabrics thus causing a much more severe problem when the tubular knitted fabric in synthetic form is processed through machinery and comes into contact with the various parts of that machinery. Thus, as will be understood, the cost factors in processing synthetic fibers, in particular, can be seriously affected by the manner in which such fabrics comprised of such fibers are handled, particularly in those instances where an entire production run may be carried out entirelyautomatically, and defects of this nature are not discovered until a substantial portion of the run is completed.

Certain other problems may arise in the heat treating of fabrics as discussed herein particularly with respect to heat treatment in conjunction with dyeing of the fabric. As will be understood, it may be appropriate to dye the fabric after heat treatment because such sequence of operations minimizes cracking of the dyed surface which takes placc if heat is applied after the dyeing procedure. However, in the past, heat setting in tubular form applied undesirable contact marks to the internal surfaces of the tubular fabric to a degree making it undesirable to subsequently dye the fabric. Thus, it is common practice to heat set the fabric in open width form and thereafter dye the fabric. Dyeing the fabric in open width form, however, presents certain problems in handling and it is much more effective and easier to be able to dye the fabric in tubular form.

In certain other instances, it may be appropriate to heat treat the fabric after it has been dyed, such as in those cases where the fabric is yarn dyed prior to knitting or in those instances where the fabric is piece-dyed for delivery to customers who desire a sequence of lengths of the same fabric of different colors delivered in tubular form. Also, it may be appropriate in certain instances to deliver the tubular knitted fabric to a customer in open width form.

In those instances where it is appropriate and desirable to deliver the fabric in open width form to a customer, in the past, such fabrics were set in open width form and such procedures may cause certain difficulties in that the fabric is not appropriately spread in all directions thus causing the application of set edges along the fabric extent, thus seriously affecting the use of the fabric for later application. On the other hand, in those instances where it was desired to obtain the fabric delivered in tubular form, certain problems arose in the past in that the heat treating procedures, because of the contact with the internal surface of the tube of the fabric, applied thereto undesirable marks.

Thus, the problem arises where in order to take advantage of heat treating fabric delivered in tubular form for easier handling during a subsequentdyeing procedure, the prior heat treating procedures were such as to affect the appropriateness for later use of the tubular fabric. The previous application of marks during the heat treating procedures in tubular. form, reduced the value of the relatively easier handling of tubular fabrics during the subsequent dyeing procedure.

The same kind of a problem arises if dyeing is applied prior to heat treating in order to minimize the cracking of the dyed surface, because the subsequent heat treating procedures set final creases in the fabric thus making it undesirable from a commercial standpoint. Accordingly, whether or not the fabric was to be delivered finally in dyed or undyed form, it became appropriate from an economic standpoint to heat treat the fabric in open width form and deliver it in that form. This served to eliminate the usual marks applied to such fabric in such heat treating procedures even though, in many instances, it might be more practical from a labor and machinery cost standpoint in subsequent handling to deliver the fabric in tubular form from a heat treating operation.

By contrast, and quite unexpectedly, it has now been found in accordance with this invention that the advantages of heat treating tubular knitted fabrics in tubular form can be utilized for subsequent handling in tubular form. This is accomplished in the absence of the application of the undesirable contact marking to such tubular fabrics and in a manner whereby the customer can obtain delivery of the fabric either in open width form or tubular form utilizing the appropriateness of heat treating in tubular form, because the setting of the fabric during such treatment is done with the fabric spread in all directions.

The applicant herein has achieved this by utilizing a new spreader configured in a form to handle the tubular knitted fabric during the heat treating operations in a manner whereby contact with the internal surfaces of the tubular knitted fabric is minimized. The spreader, in accordance herewith, is comprised of a series of criss-cross shaped frames along the longitudinal extent thereof with only the interconnection between the various segments providing sequential intermittent area contact with the internal surfaces of the tubular knitted fabrics being drawn thereover. Thus, there is only sequential area contact with the fabric surface sufficient to maintain the fabric in its spread tubular form as desired, but not to such a degree as to impart marks to the internal surface of the tubular fabric.

In addition, the contact areas of the spreader frame are arranged to be absent in those areas of the heat treating zone having the highest degree of heat application and lowest distention of the moving fabric tube, thus further minimizing marking. In addition, included with the process herein is a cooling zone placed immediately in sequence after the heat treating zone to stop any further effects of the heat treating zone on the fabric after it exits from such heat treating zone. Further in sequence with the process, in accordance herewith, a cutter arrangement may be placed immediately after the cooling zone in order to deliver the heat treated tubular fabric in open width form, if desired. Obviously, if delivery is desired in tubular form, the cutter sequence can be withdrawn for that particular operation.

Accordingly, it is one object of this invention to provide methods for heat treating tubular knitted fabric in a manner whereby contact marks on the internal surfaces thereof are substantially avoided. In addition, it is another object of this invention to heat treat tubular knitted fabric in tubular form in a manner which makes it appropriate for subsequent dyeing operations. It is a further object of this invention to provide methods for heat treating tubular knitted fabric which may be delivered after treatment in either tubular or open width form, as desired.

It is a still further object of this invention to provide methods for heat setting tubular knitted synthetic fabrics in which the fabrics are handled in such a manner during the heat setting operations that there is substantially no distortion of the fabric surface from contact with the heat treating procedures and apparatus involved.

With the foregoing and additional objects in view, this invention will now be described in more detail, and other objects and advantages thereof will be apparent from the following description, the accompanying drawings, and the appended claims.

Before describing this invention in more detail, it may be well to note that this invention has been found applicable for tubular knitted fabrics comprised of a wide variety of materials including natural fibers, such as wool and cotton, for example, as well as synthetic fibers such as nylon and polyesters, for example.

As purely illustrative of apparatus which may be used for carrying out the process of this invention, one may note the attached drawings in which a tubular knitted fabric dryer is shown with a spreader having a frame consisting of a sequence of criss-crossed segments for providing support for the tubular knitted fabric during its course through the apparatus. In addition, means are provided for supplying heat in a forced manner through the internal cavity formed by the tubular fabric passing through the apparatus, with further means for supplying compressed cooling air against the surfaces of the fabric in order to quench the effects of the heat treating procedure immediately upon exiting of the tubular knitted fabric from the heat treating zone.

IN THE DRAWINGS FIG. 1 is a longitudinal sectional view of a heat treating apparatus embodying aspects for carrying out this invention;

FIG. 2 is a perspective view of a fabric spreading device incorporated in the apparatus of FIG. 1;

FIG. 3 is a perspective view of an alternative form of spreading device which may be incorporated in the apparatus of FIG. 1; and

FIG. 4 is a somewhat simplified schematic side elevational view of a cutter device which may be incorporated in the apparatus of FIG. 1.

Referring to the drawings, in which like reference characters refer to like parts throughout the several views thereof, a heat treating device is shown designated generally at 10 with heat treating device 10 being defined by

upstanding end walls

14 and 16 supported on a base 12. It should be understood that the general arrangement of heat treating apparatus herein may be selected from any known and applicable prior art devices such as, for example, that shown and described in US. Pat. No. 3,257,735 to F. Catallo, and reference may be made to that patent for further details of general construction. It should be understood that heat treating device 10 has longitudinal side walls, not shown for clarity, for enclosing the sides of the general heat treating zone 10. Angled covers 18 and 20 serve to define the top of heat treating device 10 from the ends thereof to a central exhaust tower 64 to be described below.

Longitudinally extending baffle 24 is disposed in heat treating device 10 to define an air heating area 23 and a heat treating area 36. As can be seen in FIG. 1, baffle 24 is in spaced relation from

end walls

14 and 16 in order to allow circulation of air therearound. As can be seen in FIG. 1, further, air is drawn from the heat treating area 36 into air heating zone 23 and through

heaters

46 and 48 by the action of air blower 44 drawing the air into the opening 45 thereof.

Heaters

46 and 48 may be of any desired design for providing heat transfer'surfaces for heating the circulating air such as, for example, direct flame type gas or oil heaters, or radiant type heaters containing heat exchange tubes carrying hot water or steam. Also, electric heaters may be utilized, with the only requirement being that they provide proper heat exchange surfaces for heating the air being circulated by air blower 44.

Heat treating area 36 is further defined by baffle plates 32 and 34 which extend generally horizontal and slightly downward from

vertical walls

50, 52, and which have downwardly curved outer end portions 33. The end portions 33 of the baffles are spaced inwardly from the end walls of covers 18 and 20 to provide access to passages 28 above baffles 32, 34. Passages 28, in turn, communicate with openings 70 in

side walls

50 and 52 which communicate with exhaust tower 64. Exhaust tower 64 is comprised of a generally circular upstanding portion 54 having exhaust fan 58 disposed therein driven by motor 60 for exhausting a controlled amount of heated air from the heat treating device 10. Openings are controlled by sliding plates 72 for regulating v the amount of air exhausted by exhaust tower 64. Heat treating chamber 40 is segregated from the exhaust tower 64 by a plate 62.

As is discussed in the above noted'patent to Catallo, heat treating chamber or zone 40 has disposed therein a plurality of spaced-apart oval brackets 66 which are mounted in chamber 40 in spaced relation to define orifices 68 through which heat treating air is formed by the action of air blower 44.

As can be seen in FIG. 1, longitudinally extending spreader device 86 is disposed in heat treating device and extends from the right hand entrance end 11 thereof through the left-hand exit end 115 thereof (as shown in FIG. 1) and through a cooling chamber designated generally at 116.

The arrangement of the spreader device 86 can be best seen in FIG. 2. Spreader device 86 is comprised of a series of criss-crossed

braces

90 and 92 forming a sequential series of intermittent contact areas 94. Upper and lower contact areas 94 are connected by vertical braces 88, extending along the length of the spreader device 86. At each end of spreader device 86, the cross bars 90, 92 taper into a single end bar on each side of the spreader device with end bars 91 connected to a pair of recessed journal blocks 100 which are in turn connected by spacers 98. Each of the journal blocks 100 has a pair of rollers 102 disposed therein, which rollers are rotatable and accommodate side rollers 84 (FIG. 1) at the entrance end 11 of the heat treating device 10 and rollers 128 at the exit end 115 thereof.

Each pair of contact areas 94 at each end of vertical braces 88 are connected across the width of the spreader device by telescoping members 96 which accommodate the adjustments of the spacers 98 for varying the width of the spreader device 86, as desired. A U-shaped opener 104 extends longitudinally from the entrance journal blocks 100 for initially opening incoming material.

As can be seen in FIG. 1, tubular fabric 81 exits from conventional stripe straightener 74 and passes through a pair of spaced-apart

entrance rollers

80, 82 into treating device 10. As is shown in FIG. 1, stripe straightener 74 is mounted on upstanding support 78 which is in turn mounted on base 12. Stripe straightener 74 may be of any conventional design such as, for example, that taught in US Pat. No. 2,222,794 to Samuel Cohn, et al. to which reference can be made for further details.

Entrance rollers

80, 82 serve to guide the tubular knitted fabric 81 through the entrance end of heat treating device 10 and also to define a somewhat restricted opening for sealing the entrance from the passage of heated air therethrough so that the heated air either is forced into passage 28 or into air heating chamber 23, without, however, pressing the fabric against the frame bars.

As can be seen in FIG. 1,

vertical walls

50, 52 serve to divide heat treating area 36 into a pre-heat treating zone 38, a heat treating zone 40 and a post-heat treating zone 42. It is a feature of this invention that fabric contact areas 94 of spreader device 86 are not disposed within the heat treating zone 40 and are spaced a substantial distance therefrom so that no contact is made on tubular knitted material 81 in the area of most severe heat application. As is obvious further, tubular knitted fabric 81, as it passes through the heat treating device 10 is only supported and contacted in a sequential intermittent manner along contact areas 94 of spreader device 86 throughout the entire extent of treatment of the tubular knitted fabric 81.

In this connection, it should be noted, also, that the fabric tube is somewhat less distended in zone 40 under the action of impinging treated air, and the absence of contact in this area, therefore, becomes even more important. Contrasting this, the fabric tube is somewhat more distended or ballooned in

zones

38 and 42, thus reducing contact with areas 94 in those zones. It should be understood, further, that the usual side supporting and driving belts, not shown here for clarity, will be arranged in pairs on each side of the spreader, and will be absent in the area of heat treating zone 40 to reduce, further, any contact in this zone where the fabric is most subject to marking, as well known. This combined arrangement serves to enhance the effect of the arrangement herein, of reducing to a very substantial degree the possibility of marking the fabric.

It is a further feature of this invention that immediately upon exiting from heat treating device 10, the tubular knitted fabric is exposed to the application of cooling air in cooling device 116. Circular manifold 118 distributes cooling air to orifices 120 which orifices impinge cooling air against the outer surfaces of the tubular knitted fabric 81. The cooling air for manifold 118 may be in any appropriate form such as compressed air, for example, obtained from any wellknown source such as a compressor and it is within the purview of this invention that the compressed air may be first refrigerated in order to obtain a proper temperature control depending upon the degree of heat applied to the tubular knitted fabric 81 in the heat treating device 10, the nature of the fabric treated and the speed of treatment. Also, it should be understood that compressed air exiting from orifices 120 is under sufficient pressure in order to provide an air wall-like barrier at exit 115 of heat treating device 10 so as to prevent leakage of heated air from exit 115.

The left-hand end of spreader device 86, as viewed in FIG. 1, may be supported in a bracket device 126 which also supports exit side rollers 128. If it is desired to have a tubular knitted fabric delivered in tubular form at this point, the tubular knitted fabric as processed may then be wound on an appropriate batcher or folder device, all in well-known manner.

However, if it is desired to have the heat treated tubular knitted fabric 81 delivered in open width form, then end support bracket 126 will be replaced by a cutter arrangement 124 (FIG. 4) having a circular cutting blade 128 for slitting the tubular knitted fabric 81 into open width form. Cutter 124 may be driven in any known manner such as by motor 127 and is supported on bracket 122, as is cooling device 116. Bracket 122 is in turn supported on an upright which is supported on base 12.

Cutter 124 may be of any known arrangement for cutting tubular knitted fabric into open width form such as, for example, the arrangement taught in US. Pat. No. 3,551,969 to E. Cohn et al., which may be referred to for details of a cutting device arrangement. The fabric in open width form leaving cutting device 124 may be arranged to pass over

tension rollers

130 and 132 for subsequent wind-up, all in well-known manner. As can be seen in FIG. 4, tension roller 132 is a dancer roller connected over pulley 134 to a weight 136.

FIG. 3 is an alternative arrangement 106 of a spreader for use in the heat treating apparatus of FIG. 1 with contact areas 108 on one side thereof alternating with contact areas 110 on the opposite side thereof. Spreader device 106 is comprised of a series of longitudinally extending bars 135 interconnecting

contact areas

108, 110 with alternating low or

non-contact areas

114, 112, respectively. Longitudinally extending bars 135 are arranged with vertical braces 111 in a series of interconnected diamond-shaped frames which are in turn connected at their non-contact areas 114, l 12 with the opposite

high contact areas

110, 108, respectively, by cross braces l 15. With such arrangement of the spreader device, tubular knitted fabric passing over such a device is only contacted in alternating intermittent fashion from one side of the spreader device to the other, thus reducing contact with the internal surfaces of the tubular knitted fabric as it passes through the treating zone.

It should be understood that the arrangement in accordance herewith utilizes a variable drive interconnecting the driving rollers for controlling the feed of the tubular knitted fabric through the treating device herein in a manner to maintain proper tensioning throughout the entire extent thereof by controlling the speed of the entrance rollers in relationship to the speed of the exit rollers all in well-known fashion, and as is described in the above noted CAtallo US. Pat. No. 3,257,735, which may be referred to for further details.

The process in accordance herewith is particularly appropriate for heat setting tubular knitted synthetic fabrics, such as polyester or nylon, for example, because the fabrics can be delivered in open width form with those fabrics having been heat set in tubular form because the heat setting is done with the fabric spread in all directions, thus eliminating set edges. As is apparent, the sequence of operation in accordance herewith provides for heat setting in tubular form with immediate cooling and thereafter slitting and opening the fabric by conventional apparatus, immediately and in conjunction with the removal of the fabric from the heat setting frame of the heat treating apparatus, in accordance herewith. It should be understood, further, that by placing the cooling device 116 immediately at the exit end of the heat treating device and extending the spreader frame 86 (or 106) through the cooling device ll6, the tubular knitted fabric is heat set and cooled in its desired spread form.

In operation, as can be seen in FIG. 1, heated air is forced by air blower 44 into plenum chamber 47 around oval rings 66. The heated forced air is then forced through orifices 68 and through the interstices in the surface of the tubular knitted fabric 81 where the air passes longitudinally in both directions internally of the spread tubular knitted fabric and outwardly through interstices at each end of spreader frame 86, as shown by the arrows in FIG. 1. It is within the purview of this invention, further, that live steam may be injected into plenum chamber 47 for aiding in heat transfer against the surface of the tubular knitted fabric 81, particularly when synthetic fibers are used for making fabric 81, which brings about more rapid heatsetting of the synthetic fabrics. After the air passes back through the tubular knitted fabric in preheating zone 38 and postheating zone 42, a portion of the air may pass into passage 28 where it is drawn by fan 58 out through the top of exhaust tower 64. Another portion of the air will be recirculated back into air heating chamber 23 where it passes in heat exchange fashion through

heaters

46 and 48 to be drawn into the entrance 45 of air blower 44. Advantageously, the respective portions of the air which are recirculated and exhausted may be varied to provide for maximum operating efficiency under a variety of circumstances.

Accordingly, and as will be apparent from the foregoing, there are provided in accordance herewith, methods for heat treating tubular knitted fabrics, and particularly for heat setting synthetic fabrics such as polyesters or nylon, for example, in a manner whereby contact marks on the internal surfaces of such tubular knitted fabric are substantially avoided during such heat treating and/or heat setting. This is achieved by the utilization of a unique frame configuration for a spreader in the heat treating and/or heat setting zone therefor which frame reduces substantially the contact along the longitudinal extent of the fabric being treated. In addition, cooling arrangements are provided in combination with the heat treating methods, in accordance herewith, for defining the end of the heat treating zone and for quenching the effects of the heat treatment while the fabric being treated is spread in appropriate fashion.

Moreover, the arrangements, in accordance herewith, provide for delivery of the treated fabric in either tubular or open width form, as desired, and either before or after dyeing, thus making the invention here particularly appropriate for a variety of production techniques and the products obtained therefrom highly advantageous commercially.

While the methods herein disclosed form preferred embodiments of this invention, this invention is not limited to those specific methods, and changes can be made therein without departing from the scope of this invention which is defined in the appended claims.

What is claimed is:

l. A method for treating tubular knitted fabric; the steps which comprise circumferentially distending the fabric to be treated into internally open tubular form; advancing said fabric through a succession of treatment zones, including a pretreating zone, a treating zone and a post-treating zone; directing treating air into the tube of said fabric about its circumference within the said treating zone and causing the treating air to flow out of the tube of fabric in said pretreating and post-treating zones; maintaining the fabric free of distending contact pressures during advancement through said treating zone; distending the fabric within the pretreating and post-treating zone by restricted area pressure contact with said fabric at longitudinally and circumferentially spaced contact points, whereby marking of the internal surfaces of said treated fabric is substantially avoided.

2. A method as recited in claim 1, in which the said spaced contact points are disposed in two spaced-apart parallel rows, and said points in each of said spacedapart parallel rows are arranged in side-by-side relation along two horizontal planes.

3. A method as recited in claim 1, in which said contact points are disposed in two spaced-apart parallel rows, and said points in each of said spaced-apart parallel rows are arrangedin alternating relation along two horizontal planes whereby said treated fabric tube is subjected to constantly changing cross sectional configuration during passage over said Contact points.

4. A method as recited in claim 1, in which said treating air is heat treating air; and which also includes directing cooling air upon the distended fabric at the discharge end of said post-treatment zone, while maintaining said fabric distended by said spaced contact points.

5. A method as recited in claim 4, in which said cooling air is refrigerated compressed air.

6. A method as recited in claim 1, which includes the additional steps of removing said tubular knitted fabric from said plurality of contact points; and batching said treated fabric.

7. A method as recited in claim 6, which includes the additional step of cutting said treated tubular knitted fabric into open width form prior to said batching step.

8. A method for treating tubular knitted fabric; the

steps which comprise circumferentially distending the fabric to be treated into internally open tubular form; advancing said fabric through a succession of treating zones; directing treating air into the tube of said fabric about its circumference in one of said treating zones while maintaining the fabric free of distending contact pressures in said one zone; causing the treating air to flow out of said fabric tube in at least one other of said treating zones while distending the fabric prior to and following said one zone by restricted area pressure contact at longitudinally and circumferentially spaced contact points whereby marking of the internal surfaces of said treated fabric is substantially avoided.

Claims

1. A method for treating tubular knitted fabric; the steps which comprise circumferentially distending the fabric to be treated into internally open tubular form; advancing said fabric through a succession of treatment zones, including a pretreating zone, a treating zone and a post-treating zone; directing treating air into the tube of said fabric about its circumference within the said treating zone and causing the treating air to flow out of the tube of fabric in said pretreating and post-treating zones; maintaining the fabric free of distending contact pressures during advancement through said treating zone; distending the fabric within the pretreating and post-treating zone by restricted area pressure contact with said fabric at longitudinally and circumferentially spaced contact points, whereby marking of the internal surfaces of said treated fabric is substantially avoided.

2. A method as recited in claim 1, in which the said spaced contact points are disposed in two spaced-apart parallel rows, and said points in each of said spaced-apart parallel rows are arranged in side-by-side relation along two horizontal planes.

3. A method as recited in claim 1, in which said contact points are disposed in two spaced-apart parallel rows, and said points in each of said spaced-apart parallel rows are arranged in alternating relation along two horizontal planes whereby said treated fabric tube is subjected to constantly changing cross sectional configuration during passage over said contact points.

8. A method for treating tubular knitted fabric; the steps which comprise circumferentially distending the fabric to be treated into internally open tubular form; advancing said fabric through a succession of treating zones; directing treating air into the tube of said fabric about its circumference in one of said treating zones while maintaining the fabric free of distending contact pressures in said one zone; causing the treating air to flow out of said fabric tube in at least one other of said treating zones while distending the fabric prior to and following said one zone by restricted area pressure contact at longitudinally and circumferentially spaced contact points whereby marking of the internal surfaces of said treated fabric is substantially avoided.